Cutting device for electrotomy

ABSTRACT

A cutting device for use in electrotomy is disclosed for use with a high frequency generator to make a cut in a cutting direction. The cutting device comprises a carrier element, and first and second electrodes each connected to the high frequency generator. Each electrode has a proximal portion attached to the carrier element and an elongated distal leg portion which terminates in a distal end. An insulation element connects the distal ends to each other with predetermined spacing between them. The elongated segments oppose each other and are aligned to be co-linear with each other along the cutting direction.

BACKGROUND OF THE INVENTION

The invention relates to a cutting device for electrotomy.

It has long been known in surgery to use high-frequency AC current in afrequency range from 300 kHz to 2 MHz for the coagulation and separationof tissue, where the treated tissue is coagulated or vaporised; this isdesignated electro-coagulation or electrotomy. A differentiation must bemade between monopolar and bipolar HF thermotherapy.

With monopolar HF thermotherapy, one electrode--also designated theneutral electrode--is designed as a large surface area patient outletand is disposed near the point of intervention on the patient. The shapeof the actual working electrode--also designated the activeelectrode--is adapted to the respective application. In this way, largesurface area ball, plate or needle electrodes are used for tissuecoagulation, whilst lancet or loop electrodes are used for theseparation of tissue.

On the other hand, with bipolar HF thermotherapy, both electrodes arearranged directly next to the point of intervention so that the effectof the AC current is limited to the direct area of intervention whichprovides a high degree of safety for the patient and the user, sinceaccidents as a result of capacitative leakage current or burning on theneutral electrode can no longer occur. A further advantage of bipolar HFthermotherapy is the significantly-reduced load resistance of the tissuebetween the two electrodes which reduces the required generator powerwhilst maintaining the thermal effect.

Furthermore, HF thermotherapy can be further subdivided according to theposition of the electrodes into surface coagulation on the one hand anddeep coagulation on the other hand.

With surface coagulation, two touch electrodes disposed in parallel areused with the bipolar technique, these electrodes being placed on thetissue surface, wherein the tissue which lies beneath is heated andcoagulated as a result of the flow of current.

With deep coagulation, it is known to use needle, lancet or loopelectrodes for monopolar electrotomy. Here, electric light arcs must begenerated at the active electrode in order to vaporise tissue which liesin front of the active electrode, hence cutting the tissue. This isrelatively easy with the monopolar technique, since this only requires acertain field strength to activate a sparkover at the active electrode.On the other hand, the bipolar technique places greater demand on theconception of the electrode configuration, since the physical processesin this connection are not so simple to control. In consequence, as aresult of the necessary miniaturisation of the neutral electrode,bipolar electrode arrangements tend to change the electrode arrangementinto different and indifferent electrodes, whereupon the functionalityis effected. For this reason, only a few bipolar electrode arrangementsare known for deep coagulation, such as, for example, the ball-needlearrangement for laparoscopic electrotomy and the bipolar needleelectrode which, amongst others, is suitable for myomotherapy.

This known bipolar electrode arrangement comprises two needle electrodesdisposed in parallel which are stuck into the tissue, whereupon thetissue lying between the electrodes is heated as a result of the currentflow and is thus coagulated. However, this bipolar electrode arrangementcannot be seen as a cutting apparatus for HF surgery as a result of itsdependence on monopolar dissection hooks. Furthermore, a disadvantagewith the known bipolar electrode arrangement is the relativelylabourious placement of the electrodes with two insertion points.Furthermore, the field distribution can only be relatively inexactlydetermined by the user, since the relative position of the twoelectrodes with regard to one another cannot usually be exactlyspecified.

SUMMARY OF THE INVENTION

An objective of the invention is to produce a bipolar cutting device forelectrotomy, where the cutting quality and the ease of manipulation areimproved with regard to known bipolar cutting apparatus.

The invention includes the technical teaching of the provision of abipolar loop electrode for electrotomy, which is formed from the twoelectrodes and an insulation element arranged between the electrodes.Furthermore, the invention includes the technical teaching of replacingan electrode by an electrically-conductive fluid jet for a bipolarelectrode arrangement for electrotomy, where an electromagnetic field isbuilt up between the other electrode and the fluid jet, heating thetissue.

The cutting apparatus, according to the invention, has a bipolarelectrode arrangement wherein the two electrodes are attached to acarrier element, at least on a proximally-situated part of itslongitudinal extent to simplify manipulation and also for mechanicalfixation. In one variation of the invention, the two electrodes areelongated and are connected to one another at their distal ends by aninsulation element in order to maintain a specified electrode distance.

In the preferred embodiment of these variants, the two electrodes runtogether, at least at their distal ends, wherein the insulation elementis arranged axially between the distal ends of the two electrodes andhas an exterior cross-section which is substantially similar to theexterior cross-section of the two electrodes at their distal ends, inorder to facilitate a smooth transition. Here, the bipolar electrodearrangement has a smooth and kink-free transition in the area of theinsulation element, which is especially advantageous with linearcutting, with the cut being made parallel to the longitudinal axis ofthe electrodes.

In a further embodiment of the invention, the two electrodes each haveat least two electrode limbs, angled against one another, which lie in acommon plane wherein the distal electrode limbs of the two electrodesrun substantially straight and coaxially towards one another, in orderto permit a linear tissue cut. Hence the electrode arrangement in thisversion has a straight area which is formed from the distal electrodelimbs and the insulation element, wherein linear cutting with a cutbeing made to the longitudinal axis of the electrodes is furthersimplified, since a linear cutting channel is formed so that fineincisions are possible.

In the preferred embodiment of the invention, the two electrodes,together with the insulation element, form a bipolar loop electrode,wherein the space between the electrodes or the electrode limbs issubstantially kept free, so that apart from the linear cutting movementparallel to the plane formed by the electrodes or the electrode limbs, acutting movement at a right angle to this is also possible.

On the other hand, in another version of the invention, the twoelectrodes or the electrode limbs are substantially attached by theirentire length to the carrier element in order to attain high mechanicalload-bearing capacity and hence smaller electrode cross-sections. Sincethe mechanical load-bearing capacity in these versions is almostexclusively determined by the carrier element, very small electrodecross-sections can be realised wherein the electrical power required forcutting can be drastically reduced. Furthermore, the electrodes whichcan be used here, with a diameter which can be less than 250 μm, offerthe advantage of improved incision which is comparable to a monopolarspade electrode. Furthermore, small electrode diameters and small limblengths allow smaller cutting radii, in an advantageous manner, which isimportant in surgical dissection.

In the preferred embodiment of this variant, the carrier element isdesigned to be spatula-shaped, wherein the proximal electrode limbs arearranged along the side edges of the carrier element and are attached tothese, whilst the distal electrode limbs are arranged along the cuttingedge of the spatula-shaped carrier element and are arranged on this. Theinsulation of the two electrodes with regard to one another can takeplace between the distal ends of the two distal electrode limbs or--asin the version of the invention described beforehand--by a separateinsulation element or by the carrier element itself. However, it is herenot necessary for the insulation element or the carrier element tocompletely fill the space between the distal ends of the electrodes.Rather it is decisive that the two distal ends of the electrodes aremechanically fixed to one another by the insulation element or thecarrier element, which can also be facilitated by the two electrodesbeing connected to the carrier element along their entire length,wherein a defined air gap remains between the distal ends of the twoelectrodes. As a result of the increased stability and possibleminiaturisation with small electrode diameters, this version of theinvention is especially suitable for use in laparoscopy or in flexibleendoscopy.

With the versions of the invention described above, one of the twoelectrodes is always the active electrode also designated the differentelectrode--and the other electrode is always the neutral electrode--alsodesignated the indifferent electrode. The active electrode isdistinguished by the formation of sparkovers and thus works to separatethe tissue, whilst the neutral electrode merely functions as a returnconductor.

In the preferred embodiment of the invention, the arrangement of anactive electrode and neutral electrode can be determined by the user,whilst the cutting apparatus is so placed at the beginning of thecutting process so that one of the two electrodes touches the tissuefirst. This consciously-asymmetrical placement of the cutting apparatusmakes that electrode which has not yet been placed the active electrode,since a significantly-larger field strength is present here as a resultof the existing air gap. This air gap is then penetrated by an arc oflight as a result of the great field strength so that a cushion of steamresults which lifts the surrounding tissue from the active electrode,wherein sparkovers continually bridge the intermediate space between thetissue and the active electrode and palpate the entire tissue front sothat the tissue is separated effectively without being touched by theactive electrode. In this connection, it is important that the geometricrelationships of the two electrodes--that is, for example, theireffective lengths--are not too different, so that electrode assignmentis not already specified by the electrode arrangement. Preferably,therefore, the two electrodes in this version of the invention have thesame length in the area of the tissue contact, so that the user canfreely specify the electrode assignment by means of correspondingasymmetric placement.

On the other hand, in another version of the invention, it is providedthat a pre-specified electrode assignment is always set, irrespective ofthe operation of the cutting device by the user. Here, the twoelectrodes have strongly different geometries in the area of the tissuecontact, especially different lengths.

On the other hand, in another version of the invention only oneelectrode usually touches the tissue, whereas the electrical contactbetween the tissue and the other electrode is effected by anelectrically-conductible fluid or gas jet, which is given off by a jetin the direction of the tissue so that an electromagnetic field isformed between the one electrode and the fluid or gas jet, which heatsthe tissue.

Here, in order to simplify manipulation, the two electrodes areconnected to a carrier element which has a hollow channel for supply ofan electrically-conductible fluid, which opens into a jet-shaped openingfor emission of a fluid jet. Saline solution is preferably suitable as afluid, however the invention can also be realised by a jet of ionisedgas as a fluid. It is important here that the fluid jet is contacted bythe first electrode, which preferably occurs as a result of thejet-shaped opening being arranged in the first electrode. However, it isalso possible that the first electrode projects into the hollow channelwhich serves to supply the fluid in order to make electrical contactwith the fluid jet, or that it comprises a component part of this hollowchannel. Furthermore, in this version it is advantageous for thefunction according to the invention that the jet-shaped opening isformed and arranged in such a way that the fluid jet is given off in thedirection of the body tissue which is to be cut, and does not directlyfall on the second electrode, otherwise the two electrodes would beshort-circuited via the fluid jet. Hence, an electromagnetic field iscreated between the fluid jet and the second electrode, which leads toheating and at least partial vaporisation of the tissue, and henceeffects cutting of the tissue.

In a preferred embodiment of this variant, the fluid jet is fanned outin a wedge shape, wherein the second electrode is extended and isarranged with its longitudinal axis coaxial to the wedge-shaped fannedfluid jet. The wedge shape of the fluid jet can be effected by suitablelayout of the jet-shaped opening, however it is also possible to useseveral jet-shaped openings arranged about the circumference of thewedge axis, which each give off partial jets which unify to form thewedge-shaped fluid jet. Here, the second electrode can simply bedesigned as a needle or lancet electrode.

Other advantageous embodiments of the invention will be apparent fromthe following description of the preferred embodiments of the invention,by means of the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 As a preferred embodiment example of the invention, a cuttingdevice for electrotomy with a bipolar loop-shaped electrode arrangementin a perspective representation,

FIG. 2 The cutting device from FIG. 1 in side elevation, for explanationof the biophysical processes at the two electrodes,

FIGS. 3a, 3b A further cutting device according to the invention in sideelevation, and a detailed drawing of the cutting device,

FIGS. 4a to 4d A cutting device for electrotomy with a replaceablecutting tip in perspective representation, and

FIG. 5 A further cutting device according to the invention forelectrotomy with an electrically conductible fluid jet ascounter-electrode in perspective representation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a cutting device according to the invention for electrotomywith a bipolar electrode arrangement, which substantially comprises afirst electrode 1 and a second electrode 2 of stainless steel wire,which are attached by a high temperature adhesive to a cylindricalcarrier element 3 for mechanical fixing at their proximal ends, whichhas a formed handle 4 for manual guidance by the operator at its endsfacing away from the electrodes 1, 2. The two electrodes 1, 2 are eachdivided into a proximal electrode limb 1.1, 2.1 and a distal electrodelimb 1.2, 2.2 which is angled away from the proximal electrode limb 1.1,2.1, wherein the individual electrode limbs 1.1, 1.2, 2.1, 2.2 of thetwo electrodes 1, 2 lie in a common plane and are each designed withoutsubstantial bends along their longitudinal extent. The distal electrodelimbs, 1.2, 2.2, are mechanically joined to each other at their distalends by a cylindrical insulation element 5, so that the two electrodes1, 2, together with the insulation element 5, form a bipolar looparrangement which permits cutting movements both parallel and at rightangles to the electrode plane. However, especially advantageously, alinear cutting movement can be carried out with this cutting device, sothat in this way a linear furrow-shaped incision channel 6 is formed inthe tissue 7, through which the cutting device with the two distalelectrode limbs 1.2, 2.2 can be pulled through.

A further advantage of the loop arrangement can be seen in that theoperator retains a free view of the direct point of intervention.Moreover, the maintenance of specified electrode distances is ensured bythe insulation element 5.

In order to simplify a linear cutting movement parallel to the electrodeplane, the distal electrode limbs 1.2, 2.2 of the two electrodes 1, 2,together with the cylindrical insulation element 5, are arrangedcoaxially, wherein the insulation element 5 has the same exteriorcross-section as the distal electrode limbs 1.2, 2.2 in order to attaina smooth and step-free transition between the distal electrode limbs1.2, 2.2 and the insulation element 5.

Electrical control of the two electrodes 1, 2 takes place via separatehigh-frequency generators, which are each connected to the twoelectrodes 1, 2 via a supply line which passes through a hollow channelin the carrier element 3.

The biophysical processes during the cutting movement are clarified inthe side elevation of the cutting device represented in FIG. 2, and aredescribed in detail in the following text.

At the beginning of the cutting process, the cut is initialised, whereinassignment of the two electrodes into active electrode (differentelectrode) and neutral electrode (indifferent electrode) is selected bythe user. To do this, the operator places the cutting deviceasymmetrically on the tissue 7 in such a way that the electrode 2, whichis laid against the cutting direction, touches the tissue 7 first. Sucha consciously-asymmetrical placement of the cutting device makes theas-yet-unplaced electrode limb 2.2 the active electrode, since herethere is a substantially greater field strength as a result of thestill-existing air gap. This air gap is then penetrated by an arc oflight as a result of the great field strength, so that a cushion ofsteam 8 results which lifts the surrounding tissue 7 from the electrode2, wherein sparkovers continually bridge the intermediate space betweenthe tissue 7 and the active electrode 2 and touch the entire tissuefront so that the tissue 7 is separated from the active electrode 2virtually without being touched.

The cushion of steam 8 reduces in size towards the distal end of theactive electrode limb 2.2, as a result of reducing sparkovers in thisarea. In the area of the neutral electrode limb 1.2, the tissue 7 isthen pressed against the neutral electrode 1, as a result of thepressing force of the cutting device or by the reaction force of thetissue 7, which effects a good electrical contact between the tissue 7and the neutral electrode 1, and thus a clear assignment of the currentdensity distribution. Even with a strongly-reducing effective contactsurface of the neutral electrode 1, the assignment of active and neutralelectrodes remains initially intact. Only when the contact surface ofthe neutral electrode 1 falls below a specified minimum value can achange of the light arc and thus a change in the electrode assignmentoccur. For example, this case can occur when the indifferent electrodelimb 1.2 is almost totally removed from the cutting channel or when thecutting speed of the cutting device is equal to zero. During normalmanipulation of the represented cutting device, however, a change of thelight arc cannot be observed.

In the same way, FIG. 3a shows a cutting device for tissue separationwhich corresponds extensively with the hereinbefore-described cuttingdevice, represented in FIGS. 1 and 2, but which, however, additionallyhas a coagulation device 9 in order to stop bleeding, which isrepresented in detail in FIG. 3b in top elevation. Due to the extensiveconstructual correspondence with the cutting device hereinbeforedescribed, constructional elements in FIGS. 1 and 2 and also in FIGS. 3aand 3b are given the same reference characters, so that in thisconnection reference is made to the descriptions of the aforementionedembodiments.

The coagulation device 9 is attached on the upper side of the carrierelement 3 in a recess, so that the operator must merely turn the cuttingdevice about its longitudinal axis and place the coagulation device 9 onthe tissue in order to effect electro-coagulation to stop any bleedingwhich occurs during tissue cutting.

In this way, it is possible to separate tissue 7 and to stop anyoccurring bleeding by electro-coagulation with rapid changing betweenthe two functions. The coagulation device 9 substantially comprises aflat electrode carrier 10 of electrically insulating material and afirst electrode 11 and a second electrode 12 which comprise asilver-panadium alloy, and are additionally applied and burnt onto theelectrode carrier in a liquid state during manufacture via a fine jet.As a result of subsequent nickelling of the surface, the electrodematerial is hardened on its surface in order to give durability.

The two electrodes 11, 12 have a plurality of parallel-runningline-shaped electrode tracks which interact in a meandering fashion inorder to increase the effective electrode surface and to provide themost effective electro-coagulation possible.

Furthermore, the carrier element 3 is penetrated by a hollow channel tosupply a rinsing fluid which opens into an opening 13 in the coagulationdevice 9, through which the rinsing fluid can be ejected into the tissue7 which is to be coagulated. In this way, it is possible to preventdrying out of the tissue 7, which contributes towards an improvement inthe electrical coupling of the coagulation device 9 to the tissue 7.

FIG. 4a shows a further cutting device 14 according to the invention forelectrotomy, which substantially comprises a manipulation part 15 whichis represented in FIG. 4b, and a replaceable cutting tip 16 which isshown in FIGS. 4c and 4d.

The cutting tip 16 has a first electrode 17 and a second electrode 18for electro-thermal tissue separation, which comprise stainless steelwire with a diameter of 200 μm and which are each subdivided into aproximal electrode limb with a length of 2.5 mm and a distal electrodelimb, which is angled at right angles, wherein the proximal electrodelimbs are arranged along the side edges of a spatula-shaped carrierelement 19 and are attached to this, whereas the distal electrode limbsare arranged along the cutting edge of the spatula-shaped carrierelement 19 and are attached to this. For this, the electrodes 17, 18 areset laterally in corresponding recesses in the electrically-insulatingcarrier element 19, wherein the carrier element 19 fills the spacebetween the distal ends of the two distal electrode limbs 1.2, 2.2 andforms an insulation element 19' with a pre-specified electrode distance.The carrier element 19, which comprises ceramic, here serves on the onehand for mechanical fixing and guiding of the electrodes 17, 18 and onthe other hand for electrical insulation of the electrodes 17, 18 fromone another.

Furthermore, the carrier element 19 has a cylindrical shaft on the sidefacing away from the electrodes 17, 18 on which a saddle piece 21 isformed, which allows a mechanical and electrical connection with themanipulation part 15, wherein the connection between the cutting tip 16and the manipulation part 15 is releasable in order to allow changing ofthe cutting tip 16. The electrical connection of the cutting tip 16 withthe manipulation part 15 is via two contact flags 22 which are connectedto the two electrodes 17, 18 of the cutting tip 16.

In order to accept the cutting tip 16, the manipulation part 15 has acorresponding shape-adapted reception element 23, in which two contactflags 24 are also arranged, allowing a connection with a separate highfrequency generator via supply lines, wherein the supply lines passthrough a hollow channel in the manipulation part 15. Furthermore, themanipulation part 15 has a cylindrical sleeve 25 which can be pushed inan axial direction. For mounting or for replacement of the cutting tip16, the sleeve 25 is pushed backwards to expose the reception element ofthe manipulation part 15. Then the saddle piece 21 of the desiredcutting tip 16 is laid in the reception element 23 and the sleeve 25 isagain pushed into its closed position in order to lock the connectionbetween the cutting tip 16 and the manipulation part 15. Furthermore,the sleeve 25 can also be pushed over the cutting tip 16 in order toprotect this from mechanical damage when inserted via a trochar.

Furthermore, the manipulation part 15 is penetrated by acentrally-disposed hollow channel which extends into the cutting tip 16and which opens into an opening 26 on the upper side of the cutting tip16. In this way, it is possible on the one hand to introduce a rinsingfluid into the tissue in order to prevent electrical drying of thetissue. On the other hand, tissue substance or fluid can be sucked outof the tissue. The axially-slideable sleeve 25 here allows, in anadvantageous manner, focusing of the rinsing agent or suction streamwhen the sleeve is pushed over the opening 26.

FIG. 5 shows a further cutting device 27, according to the invention,for electrotomy with a bipolar electrode arrangement with a needleelectrode 28 and a ring-shaped electrode 29 which contact anelectrically-conductive fluid jet 30, so that an electromagnetic fieldresults between the fluid jet 30 and the needle electrode 28, whichallows warming and separation of the tissue 31.

Here, the needle electrode 28 serves as the electrode, which is attachedat its proximal end to the tip of a carrier element 32, which tapersconically in its distal area and is placed on the tissue 30 with itsdistal end. On the other hand, the ring-shaped electrode 29 works as theindifferent electrode, which comprises stainless steel and surrounds theconical end of the carrier element 32. For electrical contacting andsupply of the electrically-conductive fluid jet 30, the ring-shapedelectrode 29 has a plurality of jet-shaped openings, which aredistributed about the circumference and which allow the output of thefan-shaped expanding fluid jet 30, wherein the supply of the fluid isvia a hollow channel 33 running centrally in the carrier element 32which opens into the jet-formed openings of the ring-shaped electrode29. The ring-shaped indifferent electrode 29 thus contacts the exitingfluid jet electrically, so that the electrical circuit between the twoelectrodes 28, 29 is closed via the fluid jet 30 and the tissue 31.

The invention is not restricted in its embodiment to the preferredembodiment examples set out above. Rather a number of variants areconceivable which make use of the invention.

What is claimed is:
 1. A cutting device for use in electrotomy with ahigh frequency generator to make a cut in a cutting direction, thecutting device comprising:a carrier element; a first electrode adaptedto be connected to the high frequency generator and having a firstproximal portion attached to said carrier element and a first elongateddistal leg segment terminating in a first distal end; a second electrodeadapted to be connected to the high frequency generator and having asecond proximal portion attached to said carrier element, and a secondelongated distal leg segment terminating in a second distal end; and aninsulating element connecting said first and second distal ends to eachother with a predetermined spacing therebetween, wherein said first andsecond elongated distal leg portions oppose each other and are alignedco-linear with each other along the cutting direction, and said firstand second electrodes are disposed to lie in a plane including a linealong the cutting direction.
 2. A cutting device according to claim 1,wherein said insulation element is arranged axially between said firstand second distal ends of said electrodes and has a diameter which issubstantially the same as a diameter of said electrodes at their distalends.
 3. A cutting device according to claim 1, wherein at least one ofthe lengths of said first and second elongated distal leg segmentsportions and the diameters of said first and second elongated distal legsegments portions differ for each leg segment.
 4. A cutting deviceaccording to claim 1, wherein said two electrodes and said insulationelement together form a loop.
 5. A cutting device according to claim 1,wherein said electrodes are attached to said carrier element along aportion of their length.
 6. A cutting device according to claim 1,wherein said carrier element is spatula-shaped and has two side edgesand a cutting edge, wherein each of said first and second proximalportions are attached to respective said side edges of said carrierelement, and said elongated distal leg portions are attached to saidcutting edge of said carrier element.
 7. A cutting device according toclaim 5, wherein said carrier element has a hollow channel terminatingin an opening for at least one of supplying a stream of rinsing materialand supplying suction of body substances.
 8. A cutting device accordingto claim 7, wherein said carrier element has a shaft surrounded by asleeve, wherein an interior diameter of said sleeve is adapted to fitwith an outer diameter of said shaft, so that said sleeve can be movedaxially to focus at least one of the stream of the rinsing material andthe suction of body substances.
 9. A cutting device according to claim5, further comprising a mounting part mechanically and electricallyconnected to said carrier element by a releasable plug-in connection.10. A cutting device according to claim 1, wherein said insulationelement comprises a ceramic material.
 11. A cutting device for use inelectrotomy with a high frequency generator, the cutting devicecomprising:a carrier element; a first electrode adapted to be connectedto the high frequency generator and having a first proximal portionattached to said carrier element and a first elongated distal legportion terminating in a first distal end; a second electrode adapted tobe connected to the high frequency generator and having a secondproximal portion attached to said carrier element and a second elongateddistal leg portion terminating in a second distal end; an insulationelement connecting said distal ends to each other with a predeterminedspacing therebetween; a mounting part mechanically and electricallyconnected to said carrier element by a releasable plug-in connection,said plug-in connection comprising a saddle piece and a receptionelement adapted to fit said saddle piece; and a sleeve surrounding saidmounting part and adapted to be moved in an axial direction relative tosaid saddle piece and said reception element to secure the plug-inconnection.